1. Field of the Invention
The present invention relates to an organic electrolyte cell having a high working voltage and a high energy density.
2. Discussion of the Background
An organic electrolyte cell using an organic semiconductor having a polyacene type structure as an electrode material, wherein electrochemical doping and dedoping of electrolyte ions into the polyacene structure are employed, has a larger energy density as compared with an electric double layer capacitor employing electric charge accumulation in the electric double layer, and also has an excellent property in respect to repeating reliability of charge-discharge cycle as compared with a lithium secondary cell using lithium or its alloy as a cathode, and is widely used as a small coin-shaped cell mainly for memory backup use.
Up to now, an operating voltage for memory IC is mainly 5.0 V, and since this type of cell has an operating voltage of about 2.5 V, two unit cells are used in series for this purpose heretofore. However, recently, a driving voltage for IC is lowered, and it is therefore strongly demanded to provide a high voltage proof grade cell of at least 3.0 V which can backup the memory IC by one unit cell.
The voltage proof of this type of organic electrolyte cell is controlled mainly by electrochemical stability of an organic electrolyte. A conventional battery electrolyte employs an alkali metal salt or a quaternary onium salt as a solute and employs propylene carbonate, .gamma.-butyrolactone, acetonitrile, dimethylformamide, sulfolane or their derivatives as a solvent.
Among them, sulfolane is a solvent excellent in oxidation resistance and having a high decomposition voltage. However, since its electric conductivity is remarkably lowered at a low temperature due to the high solidifying point (freezing point), it takes a long time for charging when the charging is conducted at a low temperature and also it causes a problem of lowering an output voltage due to an internal resistance when discharging a heavy-current.